There is a great demand for water soluble or dispersible antioxidants in the food and health industries. Some of the most desirable antioxidants, polyphenols may be extracted, produced, recovered from various types of tea, such as green, black or oolong teas.
Utilizing black tea cream as a starting material for polyphenol isolation offers a number of distinct advantages. As a product of water extracts of tea leaf, the chemical constituents of cream are representative of the natural chemical constituents consumed as a beverage. The cream polyphenols have been analyzed for theaflavins and `thearubigins` by C. Powell et al., in an article entitled "Tea Cream Formation: The Contribution of Black Tea Phenolic Pigments Determined by HPLC." Journal of the Science of Food and Agriculture (1993), Vol. 63, Issue 4, p. 77. However, this method is not suitable for separation of all of the components of black tea cream.
Recovery of certain types of antioxidants has been disclosed in EP 547 370 where tea leaves are extracted with water and then using water as the eluant are fractionated.
In an article by Kyoji Yoshino et al. reported in the Biological Pharmaceutical Bulletin Vol. 17, (1994) Issue 1, p. 146 entitled "Antioxidative Effects of Black Tea Theaflavins and Thearubigin on Lipid Peroxidation of Rat Liver Homogenates Induced by text-butyl Hydroperoxide", the antioxidative activities of theaflavins and thearubigins were studied and compared to standard antioxidants such as, for example, BHT and BHA.
The prior art in approaching antioxidant or polyphenol recovery from tea has usually employed water extraction and chromatographic separation but these methods have failed to prepare either pure or relatively pure mixtures of compounds in reasonably high yields with a reasonable number of extractions or fractionations. In addition, the final composition of the mixtures is completely different from the normal distribution of theaflavins or polyphenols present in natural tea or tea cream. Thus, the methods employed by the art have not been completely satisfactory.
Accordingly, it is an object of the present invention to produce mixtures of theaflavins or polyphenols which closely approximate the distribution of theaflavins or polyphenols in natural teas or tea extracts.
A further object of the invention is to produce these theaflavins by a relatively simple process which eliminates an excessive series of fractionations with chromatographic columns.
Yet a further object of the invention is to overcome or substantially eliminate some of the problems in the art.
It has now been discovered that many, if not all of the prior art difficulties, may be overcome by the instant invention which includes preparation of tea cream from black tea extracts, solubilization of the tea cream in an appropriate water/organic liquid solvent mixtures, separation of the organic solvent soluble polyphenols from the insoluble materials and recovery of selected polyphenols from the solution by extraction and/or chromatography whereby the polyphenols/theaflavins are recovered in 90% purity using a single chromatography step and very high theoretical yield and in about the same ratio that they are found in natural tea/natural tea cream.